Gastropod egg mass deposition on a temperate,wave‐exposed coastline in New South Wales,Australia: implications for intertidal conservation

• 1. The identification and protection of known breeding grounds is a high priority for the conservation of marine biodiversity. Here, we examine the intertidal habitats used by marine gastropods for the deposition of benthic egg masses along a wave‐exposed coastline in New South Wales, Australia.
• 2. A total of 200 surveys were conducted on 13 intertidal reefs. The egg masses of 46 species were identified, with a further eight distinct types recorded but remaining unidentified. Over half of the gastropods were found to deposit egg masses exclusively on the underside of boulders. Other intertidal substrata used for gastropod egg mass deposition included vertical and horizontal exposed rock surfaces, algal fronds and sand. Only eight species were found to attach their egg masses to more than one type of substratum.
• 3. Twelve reefs were classified into three categories according to exposure to wave action and habitat diversity. The mean number of species found depositing egg masses was compared using a standard eight surveys from each site. Sub‐maximally wave‐exposed reefs with maximal habitat diversity were found to support a significantly higher species richness of gastropod egg masses, compared with maximally wave‐exposed reefs with either maximal or sub‐maximal habitat diversity (p=0.000).
• 4. Gastropods that deposit egg masses on the underside of boulders were more likely to be found on sub‐maximally wave‐exposed reefs, whereas species that deposit egg masses in all other microhabitats were equally likely to be found breeding on sub‐maximally or maximally exposed reefs.
• 5. Gastropods with pelagic larvae tended to occur at a greater number of sites than those that hatch post‐metamorphosis. A significant difference was found between species grouped according to these two developmental modes for the mean number of sites at which egg masses were recorded (p=0.008).
• 6. Variation in the species richness of gastropods found depositing egg masses on different intertidal reefs appears to be influenced by the availability of suitable boulders and exposure to wave action. These factors should be taken into consideration during the selection of locations for intertidal protected areas.

Copyright © 2004 John Wiley & Sons, Ltd.     

Combining information from benthic community analysis and social studies to establish no‐take zones within a multiple uses marine protected area

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Effects of marine reserve protection on spiny lobster (Jasus edwardsii) abundance and size at Tonga Island Marine Reserve,New Zealand

• 1. Diving surveys were undertaken to investigate the effects of marine reserve protection on spiny lobster (Jasus edwardsii) populations at Tonga Island Marine Reserve, northern South Island, New Zealand over a 2 year period from December 1998 to December 2000.
• 2. Spiny lobsters were 2.8 times more abundant overall, and mean size was 19 mm carapace length larger in shallow transects and 28 mm carapace length larger in deep transects, in the marine reserve than at adjacent fished sites. That pattern was evident despite very high variability within sites, and among sites within reserve and fished areas.
• 3. Large reproductive males were 10 times more abundant within the reserve compared to adjacent fished areas, suggesting that more eggs would be fertilized in the reserve than on the adjacent fished coast.
• 4. Estimates of size‐specific fecundity, combined with abundances of females, suggested that almost nine times more eggs would be produced in the reserve than in fished areas.
• 6. We estimate that the mean abundance of spiny lobster in the reserve has increased by 22%, 5 years after its establishment, indicating an annual population increase of 4.4%. Over the same period, abundance of spiny lobster outside the reserve has declined by 2.9% per annum.
• 7. Based on known spiny lobster movements, we suggest that marine reserves of more than 10 km length should be given priority over smaller reserves. Smaller reserves will, however, protect part of the population for at least a portion of their lifespan.
• 8. Previous studies of movement of J. edwardsii suggest that spillover from the reserve should occur, and as population density increases we predict that more spiny lobsters will move out from the reserve.

Copyright © 2002 John Wiley & Sons, Ltd.     

The Kaikōura earthquake in southern New Zealand: Loss of connectivity of marine communities and the necessity of a cross‐ecosystem perspective

1. The Mw 7.8 earthquake that struck the north‐east coast of the South Island of New Zealand in November 2016 caused extensive upheaval, of up to 6 m, over 110 km of coastline. Intertidal habitats were greatly affected with extensive die‐off of algal communities, high mortalities of benthic invertebrates, and greatly reduced ecosystem functioning, such as primary productivity. Only isolated pockets of key species remained in these areas, many of which were within protected areas around Kaikōura.
2. The loss of key species of algae and invertebrates fragmented marine populations and compromised connectivity and recovery processes because of the large dispersal distances needed to replenish populations. Severe sedimentation from terrestrial slips and erosion of newly exposed sedimentary rock compromised settlement and recruitment processes of marine species at many sites, even if distant propagules should arrive.
3. The combination of habitat disruption, loss of species and their functioning, and impacts on commercial fisheries, especially of abalone (Haliotis iris), requires multiple perspectives on recovery dynamics.
4. This paper describes these effects and discusses implications for the recovery of coastal ecosystems that include the essential involvement of mana whenua (indigenous Māori people), fishers, and the wider community, which suffered concomitant economic, recreational, and cultural impacts. These community perspectives will underpin the protection of surviving remnants of intertidal marine populations, the potential use of restoration techniques, and ultimately a successful socio‐ecological recovery.

     

Coastal geomorphology and oceanographic features shape subtidal benthic communities in management areas of central Chile

1. The spatial variation in community structure among 30 areas for the management and exploitation of benthic resources (AMEBRs) in central Chile was assessed from surveys conducted during the same spring–summer season. One hundred taxa identified in the subtidal surveys were grouped into 10 functional groups.
2. The influence and relative importance of external factors over benthic associations were assessed through nonmetric multidimensional scaling (NMDS) and path analysis. Three main categories of external factors were considered: ‘terrain traits’ (e.g. coastline exposure), ‘surface-ocean conditions’ (e.g. sea surface temperature, SST), and ‘fishery-related variables’ (e.g. cumulative landings).
3. The NMDS revealed a strong association between benthic community structure and both terrain and surface-ocean conditions (42% of variance explained by permutational multivariate analysis of variance), but not with fishery-related variables. Assemblages typical of rocky substrates were associated with larger seasonal fluctuations in SST and surface chlorophyll a. The presence of soft-bottom functional groups was associated with higher levels of surface fluorescence and larger seasonal fluctuations in a satellite-derived proxy for river-plume influence (nLw645).
4. A path analysis model for hard-bottom communities reached a 49% goodness of fit (GOF), with the presence of epifaunal filter-feeders, grazers, predators, and scavengers being significantly correlated with leathery and corticated foliose algae, which in turn depend on the fraction of rocky substrate in the AMEBR; the fraction of rocky substrate is positively correlated with coastline exposure.
5. The model for soft-bottom communities reached a 52% GOF with the presence of infaunal filter-feeders and epifaunal detritivores depending directly on SST and surface chlorophyll a. The fishery-related variables considered in the model had no apparent effect on the structure of either type of subtidal community.
6. These results provide a hierarchy of physical–biological associations determining the functional composition of subtidal benthic communities in management areas along central Chile. This knowledge may improve future assessments of ecosystem response to changes in environmental conditions and management strategies.

     

Essential fish habitats and hotspots of nekto‐benthic diversity and density in the western Mediterranean

1. Since the 1990s, most currently assessed Mediterranean nekto‐benthic stocks have been exploited above maximum sustainable yield and have declined. This study explores the co‐occurrence of essential fish habitats for the most important nekto‐benthic resources exploited by bottom‐trawl fisheries in the western Mediterranean and areas of importance for nekto‐benthic communities.
2. Fishery‐independent data obtained from Mediterranean scientific bottom‐trawl surveys were used to identify persistent hotspots of recruitment for the most important nekto‐benthic species around the Iberian Peninsula and the Balearic Islands between 2002 and 2016, as an indicator of their essential fish habitats. Likewise, hotspots of nekto‐benthic community diversity and density were also determined, as an estimate of key areas for nekto‐benthic communities.
3. Areas of overlap of persistent hotspots of recruitment and of community species richness and density were mainly found on the deep shelf and the upper slope (100–200 m and 200–500 m deep respectively).
4. These overlapping areas could be of particular interest in the development of fishery management plans aiming to implement an ecosystem approach to fisheries. Protection, through temporary or permanent closures, of the overlapping areas identified would contribute to improving both the sustainable exploitation of the main target species of bottom‐trawl fisheries and the conservation of nekto‐benthic communities.

     

Habitat use of globally threatened juvenile Chinese horseshoe crab,Tachypleus tridentatus under the influence of simulated intertidal oyster culture structures in Hong Kong

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Environmental impact of razor clam harvesting using salt in Ria Formosa lagoon (Southern Portugal) and subsequent recovery of associated benthic communities

• 1. Razor clams are found in different habitats ranging from sheltered systems (e.g. lagoons and estuaries) to open coasts. They are distributed worldwide and comprise a small number of species of high economic value. Depending on the specific habitat and species exploited, different mechanical and hand‐harvesting techniques are employed. While the environmental effects resulting from mechanized methods have been described by several authors, the impacts caused by traditional hand‐harvesting methods remain unknown. Therefore, a study was undertaken in Ria Formosa lagoon (South of Portugal) addressing the environmental effects resulting from harvesting Solen marginatus with salt.
• 2. No significant impact on the sediment was found; the main effect was an increase in salinity after covering the area with salt, which decreased rapidly with the flood tide and after a few hours had returned to pre‐harvesting levels.
• 3. No effects on benthic communities were observed, with similar fluctuation patterns recorded in control and experimental areas, the observed differences being attributed to the natural variability of benthic populations.
• 4. Based on the results obtained in the present study, a razor clam fishery using salt in intertidal areas can be considered environmentally ‘friendly’.

Copyright © 2008 John Wiley & Sons, Ltd.     

Influence of intertidal seascape on the functional structure of fish assemblages: Implications for habitat conservation in estuarine ecosystems

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Assessment of the production and dispersal of faecal waste from the sea‐cage aquaculture of spiny lobsters

Despite the rapid expansion of spiny lobster aquaculture, very little is known about its potential environmental impacts. In an effort to understand the potential impacts of sea‐cage culture of spiny lobsters, the faecal output and settling velocity of faeces of spiny lobster were quantified. These data were then used in hydrodynamic modelling to assess the dispersal pattern of faecal material from two sizes of hypothetical spiny lobster farms, so that inferences about likely benthic impacts could be made by modelling different scenarios of farm stocking density and food conversion efficiency. The overall mean settling velocity of lobster faecal strands was 0.9 ± 0.05 cm s^?1. There was a positive correlation between both the weight and density of faecal strands and their settling velocity. Conversely, neither the length nor the surface area of faecal strands was correlated with the settling velocity. Hydrodynamic modelling showed that faecal material deposition mainly occurred directly beneath the sea‐cages. The density of faecal material deposition increased proportionately with higher stocking density and FCR values. Overall, the results indicate that the deposition of faecal waste from sea‐cage lobster aquaculture is unlikely to cause widespread benthic impacts when operating to the current highest commercial stocking and feeding levels.     

Effectiveness of habitat classes as surrogates for biodiversity in marine reserve planning

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The significance of shore height in intertidal macrobenthic seagrass ecology and conservation

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The importance of bare marine sedimentary habitats for maintaining high polychaete diversity and the implications for the design of marine protected areas

• 1. Bare intertidal sedimentary habitats have received relatively little attention compared with their neighbouring vegetated habitats. An ecological comparison of benthic faunal assemblages inhabiting tropical intertidal seagrass beds and bare sediments has been made to assess the faunal similarity between the two habitats in south‐east Asia.
• 2. The poorly developed taxonomy of most invertebrate taxa in the region precluded the full identification of many faunal groups. Only the polychaetes — which accounted for 76% of all the macrofaunal organisms collected — were identified to the lowest possible taxonomic level, yielding 177 nominal species belonging to 35 families. Ecological analyses suggested that although each habitat had a distinct polychaete assemblage, there were few differences between habitats based on a range of calculated assemblage diversity metrics.
• 3. Further analyses were applied to the data to test the performance of three strategies for optimizing the selection of sites for inclusion in potential marine protected areas. Strategies were based either on the total number of species, the number of rare or endemic species, or on the level of species richness (used as a surrogate for community structure).
• 4. All three strategies consistently captured above average numbers of species at most levels of conservation intensity. The merits of each strategy are considered in turn.

Copyright © 2009 John Wiley & Sons, Ltd.     

Hierarchical methods and sampling design for conservation monitoring of tropical marine hard bottom communities

• 1. A 4-year study developed methods for annual monitoring of shallow-water tropical marine benthic communities to detect changes in spatial patterning and benthic diversity. Two low-relief sponge/octocoral communities were selected from natural colour photography to gain a broader perspective on spatial variability in the benthic community structure of similar community types.
• 2. Changes in benthic spatial patterning were studied using four methods: (i) substrata and lifeform coverage characterization, (ii) species inventories, (iii) belt quadrat measurements of taxa-level (algae, sponges, octocorals and stony corals) density, area coverage and size, and (iv) belt quadrat measurements of species-level density, area coverage and area per individual or colony.
• 3. A sampling hierarchy of multiple parameters was utilized to detect changes in benthic community diversity. Substrata and lifeform characterizations (at the taxa-versus species-level) were the least sensitive and serve as indicators of catastrophic change in community structure.
• 4. Changes in spatial patterning of the benthos that may be attributed to low-level, chronic anthropogenic disturbances can be best studied utilizing belt quadrat measurements. The use of multiple study sites and a sampling hierarchy was useful in minimizing Type II errors and to determine the level of monitoring necessary to segregate natural rates of change from anthropogenic impacts.

     

Long‐term changes of marine subtidal benthic communities in North East Asia (Yellow and Japan seas) in a global change context: A review

1. A review of the long‐term changes and variations in benthic communities and the current status of the marine invasive species (MIS) in shallow waters of the Yellow Sea (Chinese sector) and the Sea of Japan (Russian and partly Korean sectors) is presented. This paper reflects on the progress and lessons learned, recommending actions for the future about the conservation of biodiversity.
2. In the Bohai Sea, the benthic ecosystem has been degenerating due to anthropogenic activities such as overfishing and pollution since the 1950s. The dominant position of K‐strategy species is gradually being lost and replaced by R‐strategy species. In the Yellow Sea, the macrobenthic community is different from other areas due to the Yellow Sea Cold Water Mass. Many economic species have been destroyed, and the biotic structure has changed significantly due to overfishing and climate change.
3. In the Russian sector of the Sea of Japan, the macrobenthic communities in the shallow‐water soft bottom have generally been in a stable condition for the last decades, except for some heavily polluted or disturbed areas due to dredging operations. The abundance of select large invertebrate species has changed considerably due to commercial fishing and poaching. Variations in macro? and meiobenthic communities under aquaculture conditions have occurred on a local scale during the last five decades.
4. MIS show obvious differences between China and Russia in the following aspects: introduction pathways of MIS, composition and number of non‐native species, threats and impacts of MIS to native communities and ecosystems, and economic and public health impacts.
5. Long‐term monitoring programmes should be developed to reveal future biotic changes and to separate the effects of cyclic variations of benthic communities from the impacts of pollution and eutrophication. Standardization of sampling procedures is required to compare changes/alternations in benthos across various regions worldwide.

     

Repair scars preserve decadal‐scale patterns of predation intensity despite short‐term ecological disturbances

1. Recent ecological disturbances have dramatically altered the composition of rocky intertidal Pacific coast communities of North America, particularly top invertebrate predators. Predation is an important regulatory force on intertidal gastropod communities, and the depletion or loss of predators is therefore likely to have a considerable community‐wide short‐term impact. However, assessing the magnitude and nature of the resulting ecological changes may be problematic in the absence of data recording pre‐disturbance conditions.
2. Here, the effectiveness of traces of unsuccessful crab predation on gastropod shells at providing a long‐term, decadal record of predation intensity in Barkley Sound (Vancouver Island, British Columbia) was evaluated subsequent to multiple large‐scale ecological disturbances, including sea star wasting disease, abnormally high sea surface temperatures, and harmful algal blooms.
3. The frequency of failed crab attacks recorded by repair scars on six populations of the intertidal gastropod Tegula funebralis were surveyed to compare spatial patterns in predation intensity before and after disturbance (2013 and 2015 respectively). The repair frequency gradient observed in 2013 was also recorded by repair scars in 2015 (Spearman's ρ = 1, P = 0.002), and repair frequency was not affected by gastropod size in either 2013 (Spearman's ρ = 0.14, P = 0.80) or 2015 (Spearman's ρ = 0.66, P = 0.18).
4. These findings are consistent with the hypothesis that repair frequency provides decadal records of predation intensity and may be effective to establish persistent levels of predation intensity prior to disturbances in rocky intertidal habitats.

     

Complexity of river ciliate communities at a national park highlights the need for microbial conservation

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Effects of dietary carbohydrate on growth of juvenile New Zealand rock lobsters, Jasus edwardsii

The commercial aquaculture of spiny lobsters is impeded by the development of effective practical diets, which is partly due to a lack of knowledge of the digestive capabilities and nutritional needs of these species. Carbohydrates have the potential to provide a low cost energy source in practical diets for spiny lobsters. This research investigated the effect of algal carbohydrates, on the growth of juvenile rock lobsters. Juvenile lobsters, Jasus edwardsii, (10-12 mm carapace length) were provided with one of five diets; blue mussel, squid (Nototodarus gouldii), or a mussel diet partially substituted with algal carbohydrates, either agar, carrageenan or alginate over 80 days in culture. In all treatments, diet consumption and lobster growth were maintained or increased over time. Growth was highest for the mussel diet followed by the agar diet. Similar lobster growth occurred on the carrageenan and alginate diets, with the least on the squid diet. After 80 d there were significant differences in the percent lipid and glycogen stored in the mid-gut gland with highest levels of glycogen in lobsters fed the mussel only diet. Percent protein in the tail muscle was greatest for mussel fed lobsters. The mid-gut index (mid-gut weight/whole wet weight) was highest for the mussel only diet and this was similar to control lobsters at the start of the experiment. The results indicate that glycogen from mussels and agar could be used as carbohydrate source in the future development of a practical diet for spiny lobsters.     

A pseudo time‐series reveals the rapid recovery and high variability of benthic macroinvertebrate populations following catchment wildfire

1. The increasing risk of wildfire has focused attention on the timescale of the impact and recovery of river ecosystems and methods for their bioassessment.
2. An 18‐year pseudo time‐series was exploited to document patterns in benthic macroinvertebrate impact and recovery and evaluate the efficacy of alternative metrics to assess fire damage. Macroinvertebrates were surveyed by kick‐sampling and data were collected on river habitats. Details of river catchments and wildfire were collated as a GIS database.
3. Macroinvertebrate richness and abundance recovered rapidly, marked by a phase of dynamic increase, followed by relative stability (0–2 years and 3–18 years, respectively). Across sites, richness and abundance were best explained by time since fire.
4. A biotic index of general river quality was ineffective as an indicator of fire damage. While a metric of K‐selected taxa (Odonata richness) was generally indicative of fire‐affected assemblages, a contrasting metric of r‐selected taxa (percentage of chironomids, baetids, and simuliids) was not.
5. Ordination analysis revealed time as a significant determinant of community structure across sites; however, its overall statistical importance was eclipsed by habitat characteristics (water quality, shade, altitude, and latitude) that were associated with ecological variation across both recently affected sites and the putatively recovered communities.
6. These results highlight the stochastic processes – environmental and ecological – that frame the macroinvertebrate response to wildfire. This probabilistic context emphasizes the difficulties of developing indicator taxa for wildfire bioassessment and reinforces the importance of standardized survey protocols and the use of contrasting metrics in the assessment of wildfire impact on the ecological quality of rivers.

     

Habitat diversity relative to wave action on rocky shores: implications for the selection of marine protected areas

• 1. Current selection of marine protected areas in South Africa is based on objective criteria including biogeographic representation and habitat heterogeneity. This paper specifically examines rocky shores on the west coast of South Africa to determine whether they are divisible into discrete ‘habitats’ that need independent conservation.
• 2. Seventeen rocky shores spanning the full spectrum of wave exposure were compared in terms of maximum wave forces, biomass, species richness and diversity among zones and sites. Three biotic assemblages were identified, characterizing sheltered, semi‐exposed to exposed, and very exposed habitats. Differences among these were clear‐cut low on the shore but disappeared at the top of the shore where wave action was attenuated and desiccation uniformly intense.
• 3. The recognition of three discrete biologically‐defined habitats means that rocky shores cannot be regarded as a uniform habitat for conservation purposes. All three components need protection if the full spectrum of rocky‐shore communities is to be conserved.
• 4. It is argued that this approach allows habitats to be defined in an objective manner, and that once this has been done, habitat heterogeneity constitutes a better measure of conservation value of an area than a ‘hotspot’ approach based on species richness and endemism.

Copyright © 2008 John Wiley & Sons, Ltd.